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    while

    The while statement creates a loop that executes a specified statement as long as the test condition evaluates to true. The condition is evaluated before executing the statement.

    Syntax

    while (condition) {
      statement
    }
    condition
    An expression evaluated before each pass through the loop. If this condition evaluates to true, statement is executed. When condition evaluates to false, execution continues with the statement after the while loop.
    statement
    A statement that is executed as long as the condition evaluates to true. To execute multiple statements within the loop, use a block statement ({ ... }) to group those statements.

    Examples

    The following while loop iterates as long as n is less than three.

    var n = 0;
    var x = 0;
    
    while (n < 3) {
      n++;
      x += n;
    }

    Each iteration, the loop increments n and adds it to x. Therefore, x and n take on the following values:

    • After the first pass: n = 1 and x = 1
    • After the second pass: n = 2 and x = 3
    • After the third pass: n = 3 and x = 6

    After completing the third pass, the condition n < 3 is no longer true, so the loop terminates.

    Specifications

    Specification Status Comment
    ECMAScript 1st Edition. Standard Initial definition.
    ECMAScript 5.1 (ECMA-262)
    The definition of 'while statement' in that specification.
    Standard  
    ECMAScript 6 (ECMA-262)
    The definition of 'while statement' in that specification.
    Release Candidate  

    Browser compatibility

    Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
    Basic support (Yes) (Yes) (Yes) (Yes) (Yes)
    Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
    Basic support (Yes) (Yes) (Yes) (Yes) (Yes) (Yes)

    See also

    Document Tags and Contributors

    Contributors to this page: Sheppy, Marcoos, fscholz, ziyunfei, dronov, ethertank, RJacinto, Havvy, Mgjbot, Maian
    Last updated by: fscholz,
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